The present invention relates to a laser sensing means for dimensional control purposes.
Means for controlling or testing the profile of a part using a sensor are already known for the purpose of inspecting parts having an irregular shape. A machine of this type comprises a sensor mounted at the end of a sensor carrying arm and means for displacing said arm, in order that the sensor can follow the profile of the part to be inspected.
Dimensional measurements of the profile of hollow axially symmetrical parts are carried out on machines having two orthogonal plates, namely a vertically axed plate supporting the part to be inspected and a horizontally axed plate supporting the measuring head, which can be equipped with one or two sensing devices.
If it is desired to obtain an accuracy of measurement of approximately 1 micron, and bearing in mind the geometry of the parts and the nature of the materials, the sensing means must satisfy a number of different criteria. Its travel must be up to 30 mm, the sensing pressure must remain low and constant no matter what the position of the sensor in space, it must be insensitive to radial stresses and it is finally desirable for its overall dimensions to be as small as possible.
No prior art sensing means is able to satisfy all these different requirements. Accurate sensing means have large dimensions, their sensing force varies and is also several dozen grams. Conversely, the sensing means having an adequate travel or stroke and reduced overall dimensions do not permit precise measurements and are not insensitive to radial stresses.